If we're going down this route of "did a single work of fiction ruin vampires?", I'm going to say no, Twilight didn't ruin vampires. Every single popular modern vampire novel has ruined vampires. Bram Stoker romanticised vampires. Folkloric vampires were either monsters that preyed on the living, genuine threats in the dark - some traditions had them being barely human, and closer to a slobbering beast, while others had them look human but be monsters - and the horror lay in the fact that someone you loved and was close to could suddenly turn into a monster and need to be killed; it was a betrayal, and an invasion of your safe home.
Folkloric beliefs in vampires was in some cases a way to deal with loss and the fear of death, and in some cases a way to explain the progress of a disease we didn't yet understand - like when an outbreak of tuberculosis triggered the New England vampire panic.
My main problem with Twilight (mind you, I've only watched the first two movies - which are great, if you view them as unintentional comedies) is the way it romanticises an abusive and frankly creepy relationship. I mean, Bella wakes up at one point in the middle of the night, to find and uninvited Edward standing in her bedroom watching her in her sleep. And we're told that she thinks that's cute and romantic instead of incredibly creepy and invasive. Bella literally hurts herself in an effort to be closer to Edward - and we're told to think that's romantic, instead of very worrying and a cause for alarm.
Bella, abandoned by Edward for "her own good", sits motionless in a chair for months, because she simply cannot function without him, and we're told that's romantic - instead of a clear sign of a very unhealthy relationship.
The fact that Twilight vampires sparkle isn't even the start of what's troubling about those books. I mean, I haven't even gotten to the bit where the werewolf dude basically falls in love with a newborn infant. :T